Sleeper Plate for Guided Growth: Does the Plate Material Change the Risk of Tethering?

Abstract

Pediatric coronal plane deformities are commonly managed by guiding growth by placing an extraperiosteal 2-hole plate across the growth plate with 1 epiphyseal and 1 metaphyseal screw. Once the correction is achieved, removing the metaphyseal screw only (sleeper plate) has been described to facilitate easier future corrections if deformity rebounds. A complication commonly described with this approach is tethering, where the patient continues to overcorrect despite the elimination of tension across the physis. This study aims to evaluate the safety and efficacy of sleeper plates and assess the rate of tethering in stainless steel (SS) versus titanium alloy (Ti) plates. This study retrospectively reviewed patients who underwent guided growth procedures for coronal plane deformities between February 2014 and September 2023. Fifty-two sleeper plates were identified in 34 patients, out of which 30 were SS and 22 were Ti. We examined for rebounding necessitating screw reinsertion and tethering requiring plate removal. This was done by measuring mechanical lateral distal femoral angle (mLDFA), the medial proximal tibial angle (MPTA), and mechanical axis deviation (MAD) during follow-up. The median age at plate insertion was 8.6 (SS) years versus 9.7 (Ti). The median age at screw removal was 10.7 years for the SS group and 10.8 years for the Ti group after deformity correction. There was no statistically significant difference between the 2 groups with respect to age at plate insertion (P-value=0.945) and the age at screw removal (P-value=0.85). Overall, 40% of plates rebounded with 27% in SS and 59% in the Ti group (P-value=0.027), which could be explained by longer follow-up in the Ti group that was statistically different (P-value <0.001). 4/52 plates had tethering, and, of note, all the tethers were seen in the Ti group, with the median duration between screw removal and tethering first noticed being 1.1 years. All 4 patients corrected over time with the removal of the whole plate, none developed a physeal bar, and all went on to achieve normal alignment. The study had over 80% power to detect differences in tethering with a statistically significant P-value of 0.015. Sleeper plate is a viable technique for correcting coronal plane deformity, though tethering leading to overcorrection is a potential complication, especially with Ti implants. Based on our results, we advise avoiding Ti implants for sleeper plates. Level III.